CN112805114B - Method for producing a drive worm, drive worm produced by said method and drive unit having said drive worm - Google Patents

Method for producing a drive worm, drive worm produced by said method and drive unit having said drive worm Download PDF

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Publication number
CN112805114B
CN112805114B CN201980067705.6A CN201980067705A CN112805114B CN 112805114 B CN112805114 B CN 112805114B CN 201980067705 A CN201980067705 A CN 201980067705A CN 112805114 B CN112805114 B CN 112805114B
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CN
China
Prior art keywords
worm
drive
groove structure
tooth
belt
Prior art date
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Active
Application number
CN201980067705.6A
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Chinese (zh)
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CN112805114A (en
Inventor
O·赫特威格
J·包
V·赫特威克
G·乔
B·德格拉夫
D·塞蒂尔
H·特內
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Robert Bosch GmbH
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Robert Bosch GmbH
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Publication of CN112805114A publication Critical patent/CN112805114A/en
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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23P—METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS
    • B23P15/00—Making specific metal objects by operations not covered by a single other subclass or a group in this subclass
    • B23P15/14—Making specific metal objects by operations not covered by a single other subclass or a group in this subclass gear parts, e.g. gear wheels
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21H—MAKING PARTICULAR METAL OBJECTS BY ROLLING, e.g. SCREWS, WHEELS, RINGS, BARRELS, BALLS
    • B21H5/00—Making gear wheels, racks, spline shafts or worms
    • B21H5/005—Worms
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/18—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces by using pressure rollers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B21/00—Machines or devices using grinding or polishing belts; Accessories therefor
    • B24B21/006—Machines or devices using grinding or polishing belts; Accessories therefor for special purposes, e.g. for television tubes, car bumpers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B21/00—Machines or devices using grinding or polishing belts; Accessories therefor
    • B24B21/16—Machines or devices using grinding or polishing belts; Accessories therefor for grinding other surfaces of particular shape
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B49/00—Measuring or gauging equipment for controlling the feed movement of the grinding tool or work; Arrangements of indicating or measuring equipment, e.g. for indicating the start of the grinding operation
    • B24B49/14—Measuring or gauging equipment for controlling the feed movement of the grinding tool or work; Arrangements of indicating or measuring equipment, e.g. for indicating the start of the grinding operation taking regard of the temperature during grinding
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24D—TOOLS FOR GRINDING, BUFFING OR SHARPENING
    • B24D15/00—Hand tools or other devices for non-rotary grinding, polishing, or stropping
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60N—SEATS SPECIALLY ADAPTED FOR VEHICLES; VEHICLE PASSENGER ACCOMMODATION NOT OTHERWISE PROVIDED FOR
    • B60N2/00—Seats specially adapted for vehicles; Arrangement or mounting of seats in vehicles
    • B60N2/02—Seats specially adapted for vehicles; Arrangement or mounting of seats in vehicles the seat or part thereof being movable, e.g. adjustable
    • B60N2/0224—Non-manual adjustments, e.g. with electrical operation
    • B60N2/02246—Electric motors therefor
    • B60N2/02253—Electric motors therefor characterised by the transmission between the electric motor and the seat or seat parts
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H55/00—Elements with teeth or friction surfaces for conveying motion; Worms, pulleys or sheaves for gearing mechanisms
    • F16H55/02—Toothed members; Worms
    • F16H55/22—Toothed members; Worms for transmissions with crossing shafts, especially worms, worm-gears
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K7/00—Arrangements for handling mechanical energy structurally associated with dynamo-electric machines, e.g. structural association with mechanical driving motors or auxiliary dynamo-electric machines
    • H02K7/10—Structural association with clutches, brakes, gears, pulleys or mechanical starters
    • H02K7/116—Structural association with clutches, brakes, gears, pulleys or mechanical starters with gears
    • H02K7/1163—Structural association with clutches, brakes, gears, pulleys or mechanical starters with gears where at least two gears have non-parallel axes without having orbital motion
    • H02K7/1166—Structural association with clutches, brakes, gears, pulleys or mechanical starters with gears where at least two gears have non-parallel axes without having orbital motion comprising worm and worm-wheel
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/12—Both compacting and sintering
    • B22F3/16—Both compacting and sintering in successive or repeated steps
    • B22F3/164—Partial deformation or calibration
    • B22F2003/166—Surface calibration, blasting, burnishing, sizing, coining
    • E—FIXED CONSTRUCTIONS
    • E05—LOCKS; KEYS; WINDOW OR DOOR FITTINGS; SAFES
    • E05F—DEVICES FOR MOVING WINGS INTO OPEN OR CLOSED POSITION; CHECKS FOR WINGS; WING FITTINGS NOT OTHERWISE PROVIDED FOR, CONCERNED WITH THE FUNCTIONING OF THE WING
    • E05F15/00—Power-operated mechanisms for wings
    • E05F15/60—Power-operated mechanisms for wings using electrical actuators
    • E05F15/603—Power-operated mechanisms for wings using electrical actuators using rotary electromotors
    • E05F15/665—Power-operated mechanisms for wings using electrical actuators using rotary electromotors for vertically-sliding wings
    • E05F15/689—Power-operated mechanisms for wings using electrical actuators using rotary electromotors for vertically-sliding wings specially adapted for vehicle windows
    • E05F15/697—Motor units therefor, e.g. geared motors
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H55/00—Elements with teeth or friction surfaces for conveying motion; Worms, pulleys or sheaves for gearing mechanisms
    • F16H55/02—Toothed members; Worms
    • F16H55/22—Toothed members; Worms for transmissions with crossing shafts, especially worms, worm-gears
    • F16H55/24—Special devices for taking up backlash
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H57/00—General details of gearing
    • F16H57/0006—Vibration-damping or noise reducing means specially adapted for gearings
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H57/00—General details of gearing
    • F16H57/04—Features relating to lubrication or cooling or heating
    • F16H57/048—Type of gearings to be lubricated, cooled or heated
    • F16H57/0498—Worm gearings

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • Transportation (AREA)
  • Gears, Cams (AREA)
  • Gear Transmission (AREA)

Abstract

The invention relates to a method for producing a drive worm (12), which is arranged in particular on an armature shaft (14) of an electric motor drive unit (10), wherein first a worm tooth (20) is shaped by means of a rolling tool, said worm tooth having worm flanks (22) which are axially opposite on a longitudinal axis (18), and then a groove structure (24) which is concentric about the longitudinal axis (18) is formed on the worm flanks (22) by means of a further process step. The invention further relates to a worm gear (12) produced according to the method according to the invention and to a gear drive unit (10) comprising such a worm gear (12).

Description

Method for producing a drive worm, drive worm produced by said method and drive unit having said drive worm
Technical Field
The invention relates to a method for producing a drive worm, in particular arranged on an armature shaft, and to such a drive worm.
Background
A gear is known from DE 1020111006276 A1, on the tooth profile surface of which axial grooves are formed, which serve as lubricant reservoirs. By means of these grooves, lubricant can be guided to friction-critical areas of the teeth during operation, without the lubricant being completely squeezed out. Such gears can also be configured, for example, as worm gears for worm gear drives. By means of such a construction, although a reliable lubrication of the teeth can be ensured, there is a tendency here for the self-locking level (selbsthemung) of such a transmission to decrease due to continuous lubrication. However, there are applications, such as, for example, actuating drives in motor vehicles, which adjust window panes, sunroofs or seat parts, for which a high level of self-locking is desirable in the stopped state of the electric drive, in order to hold the component to be adjusted in the final position. The object of the present invention is therefore to create a transmission with reliable lubrication, wherein the level of self-locking can be adjusted in a targeted manner.
On the other hand, a worm gear is known, for example from EP 1303168 B1, in which the worm is directly rolled onto the metallic armature shaft of the electric motor. By means of the rolling method, a very smooth and firm surface of the tooth, which is configured to be wear-resistant over its entire service life, can be provided.
Disclosure of Invention
In contrast, the method and the device with the features according to the invention have the following advantages: by means of the configuration of the groove structure which extends along the circumferential direction of the threaded worm together with the worm flank (schneickenfank) of the threaded worm, on the one hand, a lubricant reservoir is provided on the worm flank which is subjected to intense loads and, on the other hand, the self-locking level of such a drive worm can be influenced in a targeted manner. In this case, firstly, the rolling produces a tooth geometry having a defined smooth surface. Thereafter, grooves extending concentrically with respect to the longitudinal axis of the drive worm are molded into the smooth surface. This has the decisive advantage that: sufficient lubricant is constantly supplied to the entire surface of the worm tooth face and at the same time there is direct contact between the tips of the groove structures and the mating teeth. This direct contact of the tips of the groove structures with respect to the mating teeth can be used to adjust the self-locking level of the teeth. The depth of the groove allows the degree of lubrication of the tooth and, at the same time, the contact surface of the tip of the groove structure with the mating tooth to be predefined.
The improvement scheme of the invention comprises: the drive worm is arranged on an armature shaft of the electric motor type drive unit; for belt grinding, a flexible grinding belt is used, which is pressed against the worm tooth surface by means of a dressing contact; manufacturing the concentric groove structure by means of a fixed grinding machine; during belt grinding, the drive worm is put into rotation and the grinding belt is pulled along the worm tooth surface by the contact piece by the torque of the worm tooth; moving the grinding belt at a relative speed lower than the peripheral speed of the worm teeth by rotation of the drive worm for structuring the concentric groove structure on the worm tooth face; manufacturing the drive worm as a separate component with a central bore along the longitudinal axis and subsequently pressing it onto the shaft of the drive unit; the rolling tool molds a continuous worm thread in a continuous process with a belt grinding process directly coupled thereto, after which the worm thread is truncated to a desired length of the drive worm; producing a surface roughness Rz of the worm tooth surface of 0.5 μm or less upon rolling, and subsequently forming a concentric groove structure having a structured roughness Rz of 0.2 μm to 10 μm; the surface roughness of the concentric groove structure can be predefined by the properties of the grinding belt and fine adjustment of the process parameters for achieving an optimal solution between a sufficient self-locking level and good efficiency of the worm gear; pressing the flexible grinding belt simultaneously against two worm flanks opposing in the thread groove by means of a dressing contact; manufacturing the drive worm as a separate component with a central bore along the longitudinal axis and subsequently pressing it onto the armature shaft; producing a surface roughness Rz of 0.1 μm or less of the worm tooth surface at the time of rolling; a concentric groove structure for accommodating lubricant is formed on the rolled worm tooth surface; the drive worm is made of metal and cooperates with a worm wheel made of plastic; the worm gear cooperates with a worm wheel made of plastic and produced by means of injection molding. The concentric groove structure in the rolled surface of the worm tooth surface can thus be formed in a very targeted manner by means of band grinding (band grinding). In this case, there is the possibility of using a grinding belt (Schleifband) to roughen the worm flanks of the drive worm in a targeted manner by: circular grooves can be milled in the circumferential direction. By selecting the grinding belt and the pressing force, the depth and the radial distance of the grooves can be predefined in a simple manner.
For this purpose, it is particularly advantageous to press the flexible grinding belt directly against the surface of the worm tooth surface with a profiled contact element. The contour of the contact piece corresponds to the molded part of the worm tooth, so that the flexible grinding belt bears in a planar manner against the worm tooth surface in a specific angular section of the drive worm.
In order to form concentric, regular grooves in the surface of the worm tooth surface, the Band-Finishing-Verfahren method is suitable. In this case, the grinding belt bears directly against the worm tooth surface in the tangential direction relative to the drive worm, so that a circular groove can be ground into the worm tooth surface in the region of the worm tooth surface in the radially outer region of the drive worm.
The threaded worm with the rolled worm flanks is preferably put into rotation, so that the helical pitch of the grinding belt along the worm flanks moves along the worm flanks, and the flanks are thereby ground over the entire axial region of the threaded worm. By such a concentric groove configuration, the roughness of such groove structure in the circumferential direction is considerably small. Thereby minimizing wear of the grooves. Whereas in a radial direction transverse to the grooves, the roughness can be adjusted in a defined manner. In the rest state of the transmission, lubricant can be retracted into the groove, so that the tip of the groove structure is in direct contact with the mating tooth, whereby the level of self-locking can be improved.
In the case of belt grinding, on the one hand, the threaded worm to be rolled is put into rotation and at the same time the grinding belt has its own feed speed. By the ratio of these two movements, the profile of the groove structure can be influenced accordingly.
Such a method is well suited for mass production of drive worms, in which long metal rods are first shaped into worms by means of continuous rolling (durchgangsrolieren), and then concentric grooves are engraved into the worm flanks by means of belt grinding. In this way, a Meter-Ware item of the threaded rod of the finished product with a concentric groove structure can be produced in practice, which can then be cut to the desired length.
It is particularly preferred if such a drive worm has a central longitudinal bore, by means of which the threaded worm can be inserted onto the drive shaft. The drive shaft can preferably be the armature shaft of the electric motor. In particular, it is advantageous in terms of manufacturing technology to press the drive worm directly onto the shaft, preferably onto a previously shaped region of the shaft, for the purpose of producing a press fit. Alternatively, the threaded sleeve can also be fastened to the shaft by means of adhesive or other material shaping.
For mass production of the threaded rod, the belt grinding can be combined directly with rolling. The grinding belt can be arranged, for example, axially immediately behind the roller plate, so that the metal rod is moved axially toward the grinding belt directly after the axial passage of the roller plate during the shaping of the spiral worm onto the metal rod. In this way, during operation, the long metal rod can be moved first in the axial direction through a rolling tool (rolling tool) and then in the same feed through the grinding device immediately thereafter in the axial direction.
In a very simple manner, a high-quality, highly compacted surface with a roughness of less than 1 μm can be produced, which has a long service life. By means of the belt-finishing, it is then possible to grind grooves into this smooth surface of the worm tooth face in the circumferential direction again, so that the surface of the groove structure is roughened in the radial direction to a roughness of rz=0.2 μm to 20 μm. The groove structure reliably prevents the worm tooth surface from being permanently connected with the mating tooth part through an uninterrupted lubricating oil film in the stop state of the transmission mechanism. The tip of the groove now rests directly against the mating tooth, whereby the desired level of self-locking can be adjusted.
The depth and profile of the groove can be adjusted not only by the characteristics of the grinding belt but also by the contact force of the grinding belt or of the contact piece. In this case, the groove structure in the rolled worm tooth surface can be changed accordingly in a simple manner, depending on the desired application of the worm gear when the requirements for the self-locking level change, without great tooling costs. Such a method, which consists of a combination of rolling and belt-finishing, is significantly less expensive than the cutting-type production method by means of milling or turning.
Such a worm gear manufactured according to the invention can be produced with a concentric groove structure which is specifically adapted to the lubricant used and to the surface of the mating toothing.
As a starting material for the drive worm, it is preferable to use a metal rod, in particular made of steel, which can be shaped plastically by means of a rolling disc for providing a very smooth surface of the worm tooth surface. The defined groove structure can be engraved into such a rolled metal surface by means of belt grinding, wherein the grooves are formed very regularly and uniformly along the circumferential direction relative to the longitudinal axis of the worm.
It is particularly advantageous to use the gear worm according to the invention in an electric motor drive unit, in which the gear housing is flanged directly to the electric motor in the axial direction. In this case, the torque is transmitted by the electric motor by means of the armature shaft to a worm drive which, in addition to the drive worm according to the invention, has a worm wheel with worm tooth parts, which is in engagement with the worm tooth surfaces. In this case, it is particularly advantageous if the worm gear is arranged directly on an armature shaft, which preferably protrudes in the axial direction into the gear housing. The worm wheel is preferably formed here, for example, as an injection molded part from plastic and is mounted directly rotatably in the gear housing. The worm wheel has, for example, an output element which then transmits the reduced torque of the electric motor to the component to be regulated or driven. In an alternative embodiment, the drive worm can also be rolled directly onto the armature shaft of the electric motor and subsequently processed by means of belt grinding. Such a drive unit according to the invention, which has a high efficiency and an adjustable level of self-locking, is suitable in a special manner for use as a window lifter, sunroof or seat adjustment drive in a motor vehicle.
Drawings
Embodiments of the present invention are illustrated in the accompanying drawings and explained in detail in the following description. Wherein is shown:
fig. 1 shows a method of manufacture according to the invention for a drive worm;
fig. 2 shows a schematic view of a worm tooth face according to the invention; and is also provided with
Fig. 3 shows a transmission drive unit according to the invention.
Detailed Description
Fig. 1 schematically shows a method for producing a worm gear 12, in which the worm gear 12 is first molded from a metal rod by means of a rolling tool. Such a threaded rod 11 with a shaped worm tooth surface 22 of the worm tooth 20 is rotatably supported in the tool holder 16 in fig. 1. The groove structure 24 is then built into the worm tooth face 22 of the worm tooth 20. For this purpose, the flexible grinding belt 30 is set in the radial direction 19 by means of the profiled contact element 32 toward the threaded rod 11 and pressed toward the worm tooth surface 22. The trimmed contact element 32 is in fig. 1 configured as a resilient contact roller, for example, made of rubber. In an alternative embodiment, the contact element 32 is embodied as a rigid rail, for example of aluminum, which is straight in the direction of the grinding paper and through which the grinding belt is drawn. The worm tooth surface 20 extends here helically around the longitudinal axis 18 of the drive worm 12. The grinding belt 30 is thus pressed in the longitudinal direction 18 against the worm tooth surface 22, wherein the drive worm 12 in the tool holder 16 is simultaneously put into rotation. By this rotation of the drive worm 12, the grinding belt 30 is moved together with the contact piece 32 along the worm tooth surface 22 over the entire length of the threaded worm 12. At the same time, the grinding belt 30 is also set in relative motion by a separate drive 31. Thereby, concentric grooves 25 are ground into the surface of the worm tooth face 22. In addition, the grinding belt 30 can be lubricated during the grinding process by means of a lubricating device 34. The grinding belt is guided tangentially to the drive worm 12 in the region of the worm tooth surface 22 during belt grinding and is pressed in the axial direction against the worm tooth surface 22 by the contact elements 32 formed by trimming. For example, the length of such a threaded rod can be as high as 1.5m, for example, for being then cut to the desired length after the grinding process.
Fig. 2 shows a detail view from the point of view of the worm tooth surface 22, which extends helically around the cylindrical base body of the drive worm 12. The worm tooth face 22 has a screw torque or pitch that determines the gear ratio of the worm gear 50. The worm tooth surface 22 is first provided with a very smooth surface by means of rolling, which has a roughness Rz of less than 0.2 μm. Thereafter, circular grooves 25 are milled into the worm tooth face 22, which preferably extend over the entire circumference of the drive worm 12 in the circumferential direction 17. The roughness Rz of the groove in the radial direction 19 is now in the range of 0.5 μm to 5 μm. Alternatively, however, the roughness Rz can also lie in the range from 0.2 μm to 20 μm. In the operating state, a lubricant is arranged in the groove 25 as a grease reservoir, which lubricant increases the efficiency in the moving state. In the rest state of the drive worm 12, the tip 44 of the groove structure 24 directly rests against the teeth of the worm wheel 52 and the lubricant can be withdrawn into the groove 25. Thus, such a worm gear 50 has a considerably high level of self-locking for preventing the reverse rotation of the worm gear 50 when the torque acts on the load side.
In fig. 3 a transmission drive unit 10 according to the invention is shown. The electric motor 48 has an armature shaft 14 which protrudes into a gear housing 56 which is connected to the electric motor 48 in the axial direction. The drive worm 12 is arranged on the armature shaft 14 and is pressed in this exemplary embodiment, in particular axially, onto a material molding 58 of the armature shaft 14. For this purpose, the worm gear 12 has a bore 26 which extends, for example, as a through-hole over the entire axial length of the worm gear 12. The worm teeth 20 engage in corresponding counter teeth 53 of a worm wheel 52, the worm wheel 52 being rotatably supported in the gear housing. The tooth flank 22 of the drive worm 12 is in this case brought into contact with the tooth of the worm wheel 52. The worm wheel 52 is preferably made of plastic as an injection molding. The surface of the teeth of the worm gear 52 can also optionally have a surface structure point by point, which can be configured as a lubricant reservoir. A circumferential groove 25 is ground on the tooth flank 22 of the drive worm 12, which also serves as a lubricant reservoir. Depending on the direction of rotation of the electric motor 48, either the first axial-side worm tooth surface 22 of the worm tooth 20 or, in the case of a reversal of the direction of rotation, the axially opposite worm tooth surface 22 of the worm tooth 20 bears against the tooth 53 of the worm wheel 52 under force loading. The free end of the armature shaft 14 is supported in the radial direction in the gear housing 56 so that the worm tooth 20 is reliably held in engagement with the tooth 53 of the worm wheel 52 even when a large load is applied. Along the longitudinal direction, the armature shaft 14 is supported by means of a damping element 62 for avoiding dry noise when moving towards the stop 60. An output element 64 is arranged on the worm gear 52, which output element transmits a torque, for example, to a component to be regulated in the motor vehicle. Preferably, such a transmission drive unit 10 is embodied as a window lifter drive or a sunroof drive or a seat regulator.
It is to be noted that a wide variety of combinations of the individual features with each other are possible in the aspects of the embodiments shown in the figures and the description. Thus, for example, the electric motor 48 can be combined with a different gear mechanism design of the worm gear mechanism 50. It is likewise possible, instead of separately produced components, to roll the drive worm 12 directly onto the armature shaft 14 and then mold the concentric grooves 25 by means of belt grinding. Likewise, it is possible to manufacture a threaded worm 12 with a blind hole 26 with which it can be inserted onto a shaft. Instead of the pressing, the drive worm 12 can also be glued or otherwise fastened to the drive shaft. The production method according to the invention can also be used in applications of the drive worm 12 outside the servo drive in a motor vehicle.

Claims (17)

1. Method for producing a drive worm (12), wherein first a worm tooth (20) is formed by means of a rolling tool, said worm tooth having worm flanks (22) which lie axially opposite one another on a longitudinal axis (18), and then a groove structure (24) which is concentric about the longitudinal axis (18) is formed on the worm flanks (22) by means of a further process step, wherein the concentric groove structure (24) is produced on the worm flanks (22) by means of belt grinding, wherein the groove structure (24) is formed such that in a standstill state of the drive, lubricant can be drawn back into the groove structure, such that a tip of the groove structure is in direct contact with a counterpart tooth, whereby the self-locking level can be improved.
2. Method according to claim 1, characterized in that the drive worm is arranged on an armature shaft (14) of an electric motor type drive unit (10).
3. Method according to any one of claims 1 or 2, characterized in that for belt grinding a flexible grinding belt (30) is used, which flexible grinding belt (30) is pressed against the worm tooth surface (22) by means of a dressing profiled contact piece (32).
4. Method according to claim 1, characterized in that the concentric groove structure (24) is manufactured by means of a fixed grinding machine.
5. A method according to claim 3, characterized in that the drive worm (12) is placed in rotation during belt grinding and the flexible grinding belt (30) is drawn here with the contact piece (32) along the worm tooth face (22) by the pitch of the worm tooth (20).
6. A method according to claim 3, characterized in that the flexible grinding belt (30) is moved by rotation of the drive worm (12) at a relative speed lower than the peripheral speed of the worm tooth (20) for structuring the concentric groove structure (24) on the worm tooth face (22).
7. Method according to claim 2, characterized in that the drive worm (12) is manufactured as a separate component with a central bore (26) along the longitudinal axis (18) and is subsequently pressed onto the shaft of the drive unit (10).
8. A method according to claim 1 or 2, characterized in that the rolling tool is used in a continuous method for moulding a continuous worm thread with a belt grinding method directly coupled thereto, after which the worm thread is taken to a desired length (13) of the drive worm (12).
9. Method according to claim 1 or 2, characterized in that a surface roughness Rz of the worm tooth surface (22) of 0.5 μm or less is produced on rolling, and that the subsequently structured concentric groove structure (24) has a structured roughness Rz of 0.2 μm to 10 μm.
10. A method according to claim 3, characterized in that the surface roughness of the concentric groove structure (24) can be predefined by the properties of the flexible grinding belt (30) and fine-tuning of process parameters for achieving an optimal solution between a sufficient level of self-locking and good efficiency of the worm gear (50).
11. A method according to claim 3, characterized in that the flexible grinding belt is pressed simultaneously against two opposite worm flanks (22) in the thread groove by means of a dressing contact (32).
12. Method according to claim 2, characterized in that the drive worm (12) is manufactured as a separate component with a central bore (26) along the longitudinal axis (18) and is subsequently pressed onto the armature shaft (14).
13. The method according to claim 9, characterized in that a surface roughness Rz of 0.1 μm or less of the worm tooth face (22) is produced upon rolling.
14. A drive worm (12) manufactured according to the method as claimed in any one of the preceding claims, characterized in that a concentric groove structure (24) for accommodating lubricant is formed on the rolled worm tooth surface (22).
15. The drive worm (12) according to claim 14, characterized in that it is made of metal and cooperates with a worm wheel (52) made of plastic.
16. The drive worm (12) according to claim 15, characterized in that it cooperates with a worm wheel (52) made of plastic, manufactured by means of injection molding.
17. An electric motor drive unit (10) having a worm gear (50) with a drive worm (12) according to any one of claims 14 to 16, characterized in that the drive worm (12) is arranged on an armature shaft (14) of an electric motor (48) which is directly flange-connected to a drive housing (56) of the worm gear (50).
CN201980067705.6A 2018-10-15 2019-10-04 Method for producing a drive worm, drive worm produced by said method and drive unit having said drive worm Active CN112805114B (en)

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DE102018217617.5A DE102018217617A1 (en) 2018-10-15 2018-10-15 Method for producing a gear worm, which is arranged in particular on an armature shaft, and such a gear worm
PCT/EP2019/076863 WO2020078734A1 (en) 2018-10-15 2019-10-04 Method for producing a gear worm which is located in particular on an armature shaft, and such a gear worm

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WO2020078734A1 (en) 2020-04-23
KR20210074294A (en) 2021-06-21
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DE102018217617A1 (en) 2020-04-16
US11904381B2 (en) 2024-02-20
CN112805114A (en) 2021-05-14

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